Chemical and physical processes combine to make primitive cells

1. abiotic synthesis of small organic molecules (amino acids)
2. small molecules join together (proteins)
3. molecules packaged into primitive cells
4. origin of self-replicating molecules

• Early earth had water vapor and simple compounds from volcanic eruptions (CO₂, CH₄, NH₃)
  • atmosphere was reducing (now controversial)
  • energy from UV or lightning
  • oceans = primordial soup of organic molecules

• Fossils help divide geologic record into 4 eons

1. Hadean
2. Archaen
3. Proterozoic

4. Phanerozoic: last 500 million years

• Recent geologic ages (3), each with unique animal life

1. Paleozoic
2. Mesozoic
3. Cenozoic

• 2^nd oxygen revolution tied to evolution of animals

• Prior to Cambrian all large animals had soft bodies
  • little evidence of predation
  • grazers, scavengers, filter feeders
  • still all marine

• Large predators evolve in early Cambrian
  • 545-525 mya
  • predator vs prey evolution
  • evolution of eyes

• Spectacular diversification of animals

• Abrupt period: only 10-20 million years!
  • troubled Darwin

• Hard skeletons and soft bodies
  • diverse body morphology (new Hox genes?)

• Bilaterally symmetrical animals
  • formation of ‘head’ region
  • organized sensory organs
  • new direction of movement

• British Columbia’s Yoho National Park
  • 60,000 unique fossils
  • one of the most diverse and well-preserved fossil sites

• Creatures from the Cambrian explosion
  • origins dating 545 to 525 million years ago

• Mudslides from land buried marine organisms
  • sediment deposited in deep-water basin next to enormous reef
  • soft and hard body fossils

• Continents = floating plates of Earth’s crust
  • plate movement = continental drift
  • a few cm a year

• Landmasses came together 3x over the previous billion years
  • yields new continents
  • new super continent in ~250 million years

• Mountains and islands form at boundaries
  • India + Eurasia = Himalayan Mtns (45 mya)
  • Appalachian Mtns ~500 mya

• Landmass change alters livable habitats
  • species distributions change
  • oceans change (Valley of Whales)
  • Pangaea (250 mya) drained shallow oceans

• Landmass change alters climate
  • Canada was once tropical

• Continental drift drives speciation
  • adapt, move or die

• 5 mass extinctions in fossil record
  • ~75% of species go extinct

• Permian extinction: 96% marine loss
  • most recent: Cretaceous (bye bye Dino)

• Causes are varied
  • volcanoes & meteors
  • massive climate change
  • ocean chemistry

• Evolution favors innovation but…
  • innovations can be wiped out

• Rapid diversification events to fill new habitats

• Occur on large scale after extinction events
  • many vacant habitats
  • favors evolutionary innovations

• Can also occur when species reaches new open habitat
  • Opportunity leads to diversification

• Dinosaur extinction → mammals
  • small & nocturnal in presence of dinosaurs